The question of legitimacy, as seen by the US, concerning the presidency of Venezuela, is simple enough. It's whether the current government at odds with US or not.
while you are 100% right, in this particular case, you are not 107% right. There are a few nuances, mostly that these guys never showed detailed election results, as the constitution mandates, meanwhile, the opposition showed decent proof they won 3:1. i.e. this guy stole the 2024 elections.
Venezuela has the biggest oil reserves in the world, and basically all politics in the country boils down to the power struggle of a US connected elite who wants to control the oil, mostly in favour of US Big Oil, and a populist leftist faction who wants to control the oil, mostly in favour of the general populace. The trouble has since forever been two-fold - when the US backed elite is out of power, the US is always working with them to cause trouble for the leftist government. And when the US backed elite is in power, it's blatant disregard for the needs of the country and general populace works towards it's own yet another downfall.
There is a snag in your narrative. The Trump administration consulted BigOil in the USoA, and most/all of the companies said that they did not want to come back here (for the companies that were expropiated in 2008), or said that they had no interest to enter (USoA players that had never been in Venezuela). And I doubt Trump risked american lives to hep BRITISH Petroleum or Royal DUTCH Shell... or repsol (Spain) or Eni (italy), or worse yet, China and India... so.... the oil american companies do not want to extract? Really?
It doesn't help that so far any leftist government has been unable to do much but buy public welfare with oil money, without building and actual strong economy for the country. This brings about things like great improvement in pretty much every metric of public welfare during the Chávez years, which coicided with good oil prices, yet a lot of it was undone when oil prices crashed.
This doesn't mean people necessarily love Maduro or Chávez or the lot, although many do, too. It's just that exactly like in every other country where the US takes to meddle for it's own interest, the US is univerally hated and people will opt for literally anyone who is not associated with them. Maybe in a similar vein like when you really hate Hillary or Biden, Trump starts to look pretty good.
Now as to the linked Blinken statement... One should by now know the difference of the actions of politics, and the rhetoric used to sell these actions. First the ends are settled on, and then unrelated talking points are constructed to reach the means needed obtain the ends. Any public statement by the government should thus be seen for what it is, bullshit not worth the breath used to utter it.
PS: I am a Venezuelan, living in Venezuela, Visiting Family in the most Militarized State (Aragua), in the most militarized city (save for Caracas), Maracay... So, eyes on site.